Is this fridge mounted in a slide, as on many fivers? If it has a sidewall top vent (as opposed to a roof vent) it should have a fan as original equipment.
OK you're plugged in. But is the fridge running on "Auto" where it should be using a 120VAC electric heating element? Or did it get punched into the "GAS" setting on the panel where it'll use LPG whether there's AC power or not?
If it's trying to run on LPG and there's a problem with the flame sensing circuit, you could be hearing it light, go out, and re-light.
